Revision surgery for periprosthetic fracture of distal femur after endoprosthetic replacement of knee joint following resection of osteosarcoma.

Purpose: Periprosthetic fracture (PPF) is one of the severe complications in patients with osteosarcoma and carries the risk of limb loss. This study describes the characteristics, treatment strategies, and outcomes of this complication. Methods: Patients were consecutively included who were treated at our institution between 2016 and 2020 with a PPF of distal femur. The treatment strategies included two types: 1) open reduction and internal fixation with plates and screws and 2) replacement with long-stem endoprosthesis and reinforcement with wire rope if necessary. Results: A total of 11 patients (mean age 12.2 years (9-14)) were included, and the mean follow-up period was 36.5 (21-54) months. Most fractures were caused by direct or indirect trauma (n = 8), and others (n = 3) underwent PPF without obvious cause. The first type of treatment was performed on four patients, and the second type was performed on seven patients. The mean Musculoskeletal Tumor Society (MSTS) score was 20 (17-23). All patients recovered from the complication, and limb preservation could be achieved. Conclusion: PPF is a big challenge for musculoskeletal oncologists, particularly in younger patients. Additionally, PPF poses a challenge for orthopedic surgeons, as limb preservation should be an important goal. Hence, internal fixation with plates and endoprosthetic replacement are optional treatment strategies based on fracture type and patient needs.

Association of circulating tumor cells and IMP3 expression with metastasis of osteosarcoma.

Background: Circulating tumor cells (CTCs) have been identified as a prognostic biomarker of tumors such as breast cancer and nasopharyngeal carcinoma, because they are obtained through a simple and noninvasive blood draw or liquid biopsy, but its clinical significance in osteosarcoma is still unclear. In this study, we analyzed the relationship between CTCs and clinicopathological features and discussed whether CTCs could be used as a biomarker for metastasis in osteosarcoma. Methods: We enrolled 50 osteosarcoma patients with Enneking Stage IIB and Stage III and detected CTCs in 5 ml of peripheral blood samples collected from patients using the Canpatrol® CTC detection platform. Subsequently, multiplex RNA in situ hybridization (RNA-ISH) based on various molecular markers was performed to identify and classify CTCs. The relationships between clinical pathological features and CTC counts, subtypes (epithelial type, E type; hybrid epithelial/mesenchymal type, H type; mesenchymal type, M type), and insulin-like growth factor mRNA-binding protein 3 (IMP3) expression in CTCs were analyzed. Results: CTCs were detected in 86% (43/50) of the osteosarcoma patients. The CTC counts, especially the total CTCs and H-type CTCs, signifcantly differed between Enneking Stage IIB and Stage III patients (P < 0.05). No significant differences were observed between the CTC count or type and other clinicopathological features (P > 0.05). There were significant differences in the expression of IMP3 in different types of CTCs, and the IMP3 positive rates in E/H/M type CTCs were 38.4, 65.6, and 62.0%, respectively (P < 0.001). Receiver operating characteristic (ROC) curve analysis showed that IMP3-positive CTC count had the best performance for diagnostic metastasis, with the largest area under the curve of 0.873 and cutoff value of four cells/5ml blood (sensitivity = 87.5%; specificity = 82.4%). Serial CTC monitoring in one patient suggested that total CTCs and H-type CTCs were associated with disease progression. Conclusion: This study demonstrates that the CTCs, especially the IMP3-positive CTCs and H/M-type CTCs, are related to the metastasis of osteosarcoma.

HMGB1 Positive Feedback Loop Between Cancer Cells and Tumor-Associated Macrophages Promotes Osteosarcoma Migration and Invasion.

Numerous studies have demonstrated the key roles of tumor-associated macrophages (TAMs) in osteosarcoma metastasis. Higher levels of high mobility group box 1 (HMGB1) promote osteosarcoma progression. However, whether HMGB1 is involved in the polarization of M2 macrophages into M1 macrophages in osteosarcoma remains largely unknown. Here, HMGB1 and CD206 mRNA expression levels were measured by a quantitative reverse transcription-polymerase chain reaction in osteosarcoma tissues and cells. HMGB1 and receptor for advanced glycation end products (RAGE) protein expression levels were measured by western blotting. Osteosarcoma migration was measured using transwell and wound-healing assays, while a transwell assay determined osteosarcoma invasion. Macrophage subtypes were detected using flow cytometry. HMGB1 expression levels were aberrantly enhanced in osteosarcoma tissues compared with normal tissues and were positively correlated with AJCC III and IV stages, lymph node metastasis, and distant metastasis. Silencing HMGB1 inhibited the migration, invasion, and epithelial-mesenchymal transition (EMT) of osteosarcoma cells. Furthermore, reduced HMGB1 expression levels in conditioned media derived from osteosarcoma cells induced the polarization of M2 TAMs to M1 TAMs. In addition, silencing HMGB1 inhibited the liver and lung metastasis of tumors and reduced the expression levels of HMGB1, CD163, and CD206 in vivo. HMGB1 was found to regulate macrophage polarization through RAGE. Polarized M2 macrophages induced osteosarcoma migration and invasion, activating HMGB1 expression in osteosarcoma cells to form a positive feedback loop. In conclusion, HMGB1 and M2 macrophages enhanced osteosarcoma migration, invasion, and EMT through positive feedback regulation. These findings reveal the significance of tumor cell and TAM interactions in the metastatic microenvironment.

En bloc resection of huge primary tumors with epidural involvement in the mobile spine using the "rotation-reversion" technique: Feasibility, safety, and clinical outcome of 11 cases.

Background: En bloc resection of spinal tumors provides better local control and survival outcomes than intralesional resection. Safe margins during en bloc resection of primary spinal tumors with epidural involvement are required for improved outcomes. The present study describes a "rotation-reversion" technique that has been used for en bloc resection of huge primary tumors in the mobile spine with epidural involvement and reported the clinical outcomes in these patients. Methods: All patients with primary spinal tumors who were treated with the rotation-reversion technique at our institution between 2015 and 2021 were evaluated retrospectively. Of the patients identified, those with both huge extraosseous soft-tissue masses and epidural involvement were selected for a case review. Clinical and radiological characteristics, pathologic findings, operative procedures, complications, and oncological and functional outcomes of these patients were reviewed. Results: Of the 86 patients identified with primary spinal tumors who underwent en bloc resection using the rotation-reversion technique between 2015 and 2021, 11 had huge extraosseous soft-tissue masses with epidural involvement in the mobile spine. The average maximum size of these 11 tumors was 8.1 × 7.5 × 9.7 cm. Median follow-up time was 28.1 months, mean operation time was 849.1 min (range 465-1,340 min), and mean blood loss was 6,972.7 ml (range 2,500-17,700 ml), with 10 (91%) of the 11 patients experiencing perioperative complications. The negative margin rate was 91%, with only one patient (9%) experiencing local recurrence. Ten patients were able to walk normally or with a crutch at the last follow-up, whereas one was completely paralyzed preoperatively. Conclusion: The rotation-reversion technique is an effective procedure for the en bloc resection of huge primary spinal tumors, with the extension of invasion in selected patients including not only the vertebral body but also the pedicle and part of the posterior arch.

Image-guided percutaneous biopsy and pathological diagnosis in atypical tuberculous spondylitis: a case series and clinical outcomes.

Background: Tuberculous spondylitis can be difficult to distinguish from alternative spinal pathologies such as malignancy, particularly if the imaging features are not typical. Biopsy and histopathological analysis are facilitative to the early and accurate diagnosis of atypical tuberculous spondylitis and the clinical management. The purpose of this study is to describe some of the atypical imaging features of tuberculous spondylitis diagnosed by image-guided percutaneous biopsy, as well as associated treatment outcomes. Methods: We performed a retrospective analysis of all patients diagnosed with tuberculous spondylitis after image-guided percutaneous biopsy at The Third Affiliated Hospital of Southern Medical University between 2013 and 2020. Of the patients identified, those with atypical imaging features were selected for case review. All patients were given anti-tuberculous medication treatment with or without surgery. The imaging features, histological and microbiological results, and clinical presentations and outcomes were evaluated. Neurological function was evaluated according to the Frankel grading system. The clinical outcomes were evaluated by Visual Analogic Scale (VAS) scores for pain, imaging [X-ray, computed tomography (CT), and magnetic resonance imaging (MRI)] results, and laboratory examinations. Comparison of VAS scores was made by Student t-test. Results: Of the 102 patients identified with tuberculous spondylitis between 2013 and 2020, eight patients (two females and six males) with a mean age of 41.6 years (range, 18-61 years) demonstrated atypical imaging findings, including central vertebral body lesion, multiple skip vertebral lesions, extradural mass lesion and anterior subperiosteal lesion. All eight patients received anti-tuberculous medication treatment, and six underwent surgery. One patient developed a pleural effusion after debridement of the thoracic lesion. The mean follow-up period was 16.2 months (6-37 months). The VAS scores before treatment and at the final follow-up showed significant differences (7.25±1.49 and 0.0±0.0, respectively, P<0.01). Improved neurological function were observed in all patients. Solid fusion and osteogenic osteosclerosis were observed at the final follow-up, and no recurrence was observed in any cases. Conclusions: All eight patients had a good prognosis. Image-guided biopsy and histopathological analysis are helpful for the early diagnosis of tuberculous spondylitis, especially when imaging features are not typical for this condition.

A Comprehensive Understanding of the Genomic Bone Tumor Landscape: A Multicenter Prospective Study.

Complexity and heterogeneity increases the difficulty of diagnosis and treatment of bone tumors. We aimed to identify the mutational characterization and potential biomarkers of bone tumors. In this study, a total of 357 bone tumor patients were recruited and the next generation sequencing (NGS)-based YuanSu450 panel, that includes both DNA and RNA sequencing, was performed for genomic alteration identification. The most common mutated genes in bone tumors included TP53, NCOR1, VEGFA, RB1, CCND3, CDKN2A, GID4, CCNE1, TERT, and MAP2K4. The amplification of genes such as NCOR1, VEGFA, and CCND3 mainly occurred in osteosarcoma. Germline mutation analysis reveal a high frequency of HRD related mutations (46.4%, 13/28) in this cohort. With the assistance of RNA sequencing, 16.8% (19/113) gene fusions were independently detected in 20% (16/79) of patients. Nearly 34.2% of patients harbored actionable targeted mutations, of which the most common mutation is CDKN2A deletion. The different mutational characterizations between juvenile patients and adult patients indicated the potential effect of age in bone tumor treatment. According to the genomic alterations, the diagnosis of 26 (7.28%) bone tumors were corrected. The most easily misdiagnosed bone tumor included malignant giant cell tumors of bone (2.8%, 10/357) and fibrous dysplasia of bone (1.7%, 6/357). Meanwhile, we found that the mutations of MUC16 may be a potential biomarker for the diagnosis of mesenchymal chondrosarcomas. Our results indicated that RNA sequencing effectively complements DNA sequencing and increased the detection rate of gene fusions, supporting that NGS technology can effectively assist the diagnosis of bone tumors.

Application of a novel porous tantalum implant in rabbit anterior lumbar spine fusion model: in vitro and in vivo experiments.

BACKGROUND: Some porous materials have been developed to enhance biologic fusion of the implants to bone in spine fusion surgeries. However, there are several inherent limitations. In this study, a novel biomedical porous tantalum was applied to in vitro and in vivo experiments to test its biocompatibility and osteocompatibility. METHODS: Bone marrow-derived mesenchymal stem cells (BMSCs) were cultured on porous tantalum implant. Scanning electron microscope (SEM) and Cell Counting Kit-8 assay were used to evaluate the cell toxicity and biocompatibility. Twenty-four rabbits were performed discectomy only (control group), discectomy with autologous bone implanted (autograft group), and discectomy with porous tantalum implanted (tantalum group) at 3 levels: L3-L4, L4-L5, and L5-L6 in random order. All the 24 rabbits were randomly sacrificed at the different post-operative times (2, 4, 6, and 12 months; n = 6 at each time point). Histologic examination and micro-computed tomography scans were done to evaluate the fusion process. Comparison of fusion index scores between groups was analyzed using one-way analysis of variance. Other comparisons of numerical variables between groups were made by Student t test. RESULTS: All rabbits survived and recovered without any symptoms of nerve injury. Radiographic fusion index scores at 12 months post-operatively between autograft and tantalum groups showed no significant difference (2.89 ±â€Š0.32 vs. 2.83 ±â€Š0.38, F = 244.60, P = 0.709). Cell Counting Kit-8 assay showed no significant difference of absorbance values between the leaching liquor group and control group (1.25 ±â€Š0.06 vs. 1.23 ±â€Š0.04, t = -0.644, P = 0.545), which indicated the BMSC proliferation without toxicity. SEM images showed that these cells had irregular shapes with long spindles adhered to the surface of tantalum implant. No implant degradation, wear debris, or osteolysis was observed. Histologic results showed solid fusion in the porous tantalum and autologous bone implanted intervertebral spaces. CONCLUSION: This novel porous tantalum implant showed a good biocompatibility and osteocompatibility, which could be a valid biomaterial for interbody fusion cages.

MiR-455-3p regulates early chondrogenic differentiation via inhibiting Runx2.

The expression of miR-455-3p has been shown to be up-regulated in chondrogenesis of mesenchymal stem cell, but its role in different stages during chondrogenesis remains unknown. Here, we show that miR-455-3p is increased in ATDC5 cells from 0 d to 21 d, but rapidly decreases at 28 d, and a similar expression kinetic is detected in the development of mouse embryos. We show that miR-455-3p functions as an activator for early chondrogenic differentiation, most likely by inhibiting the expression of Runt-related transcription factor 2 (Runx2) as indicated by luciferase reporter assays. In conclusion, miR-455-3p may activate early chondrogenesis by directly targeting Runx2.

[EXPRESSIONS OF CARTILAGE DEGENERATIVE RELATED GENES AND microRNAs IN TORN MENISCUS].

OBJECTIVE: To investigate the expressions of cartilage degenerative related genes in meniscus, and to evaluate the potential effect of meniscal damage on cartilage degeneration, and to analyze the relationship between microRNAs (miRNAs) expression and cartilage degeneration. METHODS: Meniscal tissue was collected from 5 patients undergoing partial meniscectomy between September 2012 and October 2013 (experimental group), and normally meniscal tissue without tearing from amputees was used as controls (control group). Pathological changes of menisci were observed; and real-time fluorescent quatitative PCR was performed to examine the relative expression levels of cartilage degenerative related genes and miRNAs: Aggrecan (ACAN), type X collagen (COL10A1), matrix metalloproteinases 13 (MMP-13), CCAAT enhancer binding protein ß (CEBP-ß), a disintegrin and metalloproteinase with thrombospondinmotif 5 (ADAMTS-5), miR-193b, miR-92a, and miR-455-3p in meniscus. RESULTS: There were varying degrees of degenerative pathological changes in torn meniscus of experimental group. Compared with normal meniscus of control group, the expression of ACAN was decreased, while the expressions of COL10A1, CEBP-ß, ADAMTS-5, and MMP-13 were increased in torn meniscus of experimental group; and significant difference was found (P < 0.05) except ACAN and MMP-13 (P > 0.05). The expressions of miR-92a, miR-455-3p, and miR-193b in torn meniscus of experimental group were significantly higher than those in normal meniscus of control group (P < 0.05). CONCLUSION: Meniscal tissue has the intrinsic tendency of degeration after meniscus tear. The torn meniscus has greater stimulative impact on cartilage degeneration than normally morphological meniscus without tearing. The cartilage degenerative related miRNAs, including miR-193b, miR-92a, and miR-455-3p may contribute to the up-regulation of osteoarthritis.

Presence and function of microRNA-92a in chondrogenic ATDC5 and adipose-derived mesenchymal stem cells.

The aim of the present study was to investigate the presence and biological function of microRNA-92a (miR-92a) in chondrogenesis and cartilage degeneration. Human adipose­derived mesenchymal stem cells (hADSCs) in micromass and chondrocyte­like ATDC5 cells were induced to chondrogenesis, and primary human/mouse chondrocytes (PHCs/PMCs) and chondrogenic ATDC5 cells were stimulated with interleukin­1ß (IL­1ß). An miR­92a mimic/inhibitor was transfected into the ATDC5 cells using lipofectamine 2000. Gene expression was analyzed using reverse transcription­quantitative polymerase chain reaction. Alcian blue was used to stain the cartilage nodules and chondrogenic micromass. The potential target genes, signaling pathways and functions of miR­92a were examined using miRanda, miRDB, CLIP­Seq, TargetScan and Kyoto Encyclopedia of Genes and Genomes. The expression of miR­92a was elevated in the chondrogenic ATDC5 cells and hADSCs, and also in the IL­1ß­induced ATDC5 cells, PMCs and PHCs. Forced expression of miR­92a enhanced the expression levels of col9a2 and aggrecan. A total of 279 genes were predicted as potential target genes of miR­92a. The phosphoinositide 3­kinase/PI3K)­Akt, ErbB and focal adhesion kinase pathways, extracellular matrix (ECM)­receptor interaction and the mammalian target of rapamycin (mTOR) signaling pathway were suggested to mediate the effects of miR­92a on chondrogenesis and cartilage degeneration. These results demonstrated that miR­92a was involved in chondrogenesis and the chondrocyte response induced by IL­1ß. miR­92a positively contributed to the expression of col9a2 and of aggrecan.

The Role of MicroRNA-381 in Chondrogenesis and Interleukin-1-ß Induced Chondrocyte Responses.

AIM: The molecular pathways regulating cartilage degradation are unclear. miR-381 was identified as a putative regulator of chondrogenesis related genes. Here, we examined its role in chondrogenesis and osteoarthritic cartilage degeneration. METHODS: miR-381 expression was assessed in vitro in response to IL-1ß stimulation in primary human (PHC) and mouse (PMC) chondrocytes, and ATDC5 derived chondrocytes; and in vivo in mouse embryos and human osteoarthritic cartilage. The effects of miR-381 on chondrogenesis and NF-kB signaling were assessed using a synthetic RNA mimic or inhibitor and luciferase assay, respectively. Upstream regulators of miR381 were probed using siRNA or overexpression plasmids for Sox9 and Runx2. RESULTS: miR-381 expression was elevated in chondrogenic and hypertrophic ATDC5 cells. miR-381 was induced in vitro by IL-1ß in ATDC5 cells, PMCs, and PHCs, and was expressed in areas of cartilage degradation or absorption in vivo. Overexpression of Runx2 or Sox9 increased miR-381 expression in ATDC5 cells. miR-381 suppressed expression of collagen, type II, alpha 1, and enhanced expression of metalloproteinase-13 (MMP-13), but did not regulate NFKBIA and NKRF activity. CONCLUSION: miR-381 was highly expressed during chondrogenesis and in arthritic cartilage. It may contribute to absorption of the cartilage matrix by repressing type II collagen and inducing MMP-13.

MiR-193b regulates early chondrogenesis by inhibiting the TGF-beta2 signaling pathway.

Cartilage generation and degradation are regulated by miRNAs. Our previous study has shown altered expression of miR-193b in chondrogenic human adipose-derived mesenchymal stem cells (hADSCs). In the current study, we investigated the role of miR-193b in chondrogenesis and cartilage degradation. Luciferase reporter assays showed that miR-193b targeted seed sequences of the TGFB2 and TGFBR3 3'-UTRs. MiR-193b suppressed the expression of early chondrogenic markers in chondrogenic ATDC5 cells, and TNF-alpha expression in IL-1b-induced PMCs. In conclusion, MiR-193b may inhibit early chondrogenesis by targeting TGFB2 and TGFBR3, and may regulate inflammation by repressing TNF-alpha expression in inflamed chondrocytes.

Resistin stimulates expression of chemokine genes in chondrocytes via combinatorial regulation of C/EBPß and NF-κB.

To further investigate the regulation role of two chemokine genes CCL3 and CCL4 in chondrocytes in response to resistin, human primary chondrocytes and T/C-28a2 cells were cultured. The function of resistin on the chemokine genes, and the expression of C/EBPß, NF-κB isoforms were tested using qPCR. The methods used to investigate timed co-regulation of C/EBPß and NF-κB were NF-κB inhibitor (IKK-NBD) and C/EBPß inhibitor (SB303580) treatments, and subcellular localization, with or without resistin stimulation. Results showed that resistin could increase the up-regulation of chemokine genes independently. Resistin increased the expression of C/EBPß and NF-κB isoforms. C/EBPß regulated basal activity and steadily increased over time up to 24h with resistin. NF-κB was up-regulated upon induction with resistin, peaking at 4 h. C/EBPß and NF-κB co-enhanced the chemokines expression; inhibition of their activity was additive. The timing of activation in chondrocytes was confirmed by subcellular localization of C/EBPß and c-rel. Chondrocytes react to resistin in a non-restricted cell-specific manner, utilizing C/EBPß and NF-κB in a combinatorial regulation of chemokine gene expression. The activity of C/EBPß is augmented by a transient increase in activity of NF-κB, and both transcription factors act independently on the chemokine genes, CCL3 and CCL4. Thus, resistin stimulates CCL3 and CCL4 through combinatorial regulation of C/EBPß and NF-κB in chondrocytes.

[Selectively upward placement of acetabular implants in patients with anatomically abnormal acetabulum during total hip arthroplasty].

OBJECTIVE: To investigate the method and effectiveness of selectively upward placement of acetabular implants in patients with anatomically abnormal acetabulum during total hip arthroplasty (THA). METHODS: Twenty-six cases (26 hips) of anatomically abnormal acetabulum received THA between January 2005 and December 2010, including 22 cases of developmental dysplasia of the hip, 3 cases of osteonecrosis of the femoral head, and 1 case of post-traumatic arthritis. There were 5 males and 21 females with an average age of 52.3 years (range, 35-67 years). The left hip was involved in 11 cases and the right hip in 15 cases. The preoperative Harris score was 45.85 +/- 10.04. The anteroposterior X-ray films and CT scan of the pelvis, anteroposterior and lateral X-ray films of the femur, and TraumaCad analysis were performed routinely before operation. The principles of acetabular implants were that more than 70% of the bone-implant interface was covered, and the upward distance of acetabular implant was less than 15 mm. RESULTS: Acetabular implants were placed within 5 mm from the anatomical rotation center in 11 cases. The upward distance of acetabular implant was 5-10 mm in 8 cases and was 10-15 mm in 7 cases. No bone fracture or nerve injury was observed intraoperatively. All incisions healed by first intention, and no infection or lower limb deep venous thrombosis occurred. One case had dislocation at 3 days after operation, and was cured after reduction and conservative treatment. The follow-up time ranged from 15 to 71 months (mean, 34 months). The Harris score was 91.42 +/- 3.59, showing significant difference when compared with preoperative score (t = 20.099, P = 0.000). The Harris scores were 92.09 +/- 4.04 in patients having less than 5 mm upward distance, 91.25 +/- 2.82 in patients having 5-10 mm upward distance, and 90.57 +/- 3.95 in patients having 10-15 mm upward distance, showing no significant difference (F = 0.377, P = 0.690). No loosening or subsidence of the implant was observed by X-ray film during the follow-up. CONCLUSION: The acetabular implants should be placed as close to anatomical rotation center as possible according to the principle. However, appropriate upward distance of the acetabular implants (< or = 15 mm) could be acceptable to meet 70% coverage of bone-implant interface and the implant stability. A satisfactory mid-term effectiveness can be obtained, but long-term effectiveness should be further investigated.

A comparison of biomechanical changes on femoral head following rotational acetabular osteotomy and eccentric rotational acetabular osteotomy in normal cadaveric hip.

PURPOSE: Both rotational acetabular osteotomy (RAO) and eccentric rotational acetabular osteotomy (ERAO) are effective procedures for young patients with developmental dysplasia of the hip. However, no comparative study of biomechanical changes has been reported following these two procedures. We therefore explored the stress changes on femoral head after RAO and ERAO under different load conditions. MATERIALS AND METHODS: Twelve female cadaveric hips without deformity were divided into RAO group and ERAO group. Stress value on femoral head was measured preoperatively and postoperatively after the vertical force was loaded on the cadaveric spine from 0 to 500 N. Stress change value was then calculated base on the measurements. RESULTS: In the RAO group, preoperative stress increased when loading on spine became larger, but postoperative stress changed its increasing trend into decreasing when the load was greater than 200 N (turning point). Same phenomenon was found in the ERAO group (turning point was 300 N). However, the difference between preoperative and postoperative stress was not statistically significant in both RAO and ERAO groups. Stress change value from each procedure showed similar trends. With the load growth, stress change increased firstly and then decreased, but the difference between RAO and ERAO was not statistically significant. CONCLUSIONS: Both RAO and ERAO could correct the abnormal biomechanical effect of dysplastic hip; moreover, they may have similar biomechanical effects on femoral head, obtaining the same clinical outcomes. Non-biomechanical factors (surgical trauma, technical complexity, etc.) also play important roles in procedure selection.

Presence of interleukin-17C in the tissue around aseptic loosened implants.

PURPOSE: The most common long-term complication of joint arthroplasty is aseptic loosening. The proinflammatory cytokines secreted by macrophages are involved in aseptic loosening. Recently, a novel proinflammatory cytokine IL-17C was reported to participate in inflammatory diseases by synergising with proinflammatory cytokines. However, the relationship between IL-17C and the aseptic loosening is unclear. METHODS: The tissues around aseptic loosened implants were collected during revision surgery and handled by formalin fixation and embedded in paraffin. The presence of IL-17C in the tissues around the aseptic loosened implants was investigated in 12 aseptic loosening patients using immunofluorescence. RESULTS: The presence of IL-17C protein in the tissues around aseptic loosened implants was detected by immunofluorescence. There are no statistical differences between optical density of IL-17C in aseptic loosening samples and in rheumatoid arthritis samples (positive control). CONCLUSIONS: These results suggest the presence of IL-17C in aseptic loosening. Interleukin-17C was related to the inflammation of aseptic loosening, possibly by contributing to the inflammation and osteolysis in the tissues surrounding aseptic loosened implants.

Wear particles promote endotoxin tolerance in macrophages by inducing interleukin-1 receptor-associated kinase-M expression.

Toll-like receptors (TLRs) recognizing pathogen-associated molecular patterns (PAMP) play a role in local immunity and participate in implant-associated loosening. TLRs-mediated signaling is regulated by interleukin-1 receptor-associated kinase-M (IRAK-M). Our previous studies have proved that IRAK-M is induced by wear particles in macrophages from periprosthetic tissues. In this study, the IRAK-M-related mechanisms were further explored by lipopolysaccharide (LPS) and/or titanium (Ti) particles stimulations and small interfering RNAs (siRNAs). The protein level of IRAK-M was studied using western blotting and tumor necrosis factor-α (TNF-α), and interleukin-1ß (IL-1ß) levels were measured using ELISA. Results showed that in RAW264.7 cells stimulated by LPS after Ti particle pre-exposure, IRAK-M was slightly changed, compared with LPS stimulation. And levels of TNF-α and IL-1ß in cultures stimulated by LPS first after Ti particle pre-exposure were lower than in the other two groups which were stimulated by LPS with or without Ti particles (p < 0.001), whereas there were no statistic differences between the later two (p > 0.05). The cytokines were lowest in Ti particles alone stimulation. After siRNAs silenced, IRAK-M-deficient cells exhibited increased expression of the cytokines in LPS stimulation after Ti particle pre-exposure and when stimulated with Ti particles alone. Our findings suggest that debris-induced IRAK-M decreases foreign body reactions, but at the same time, the over-expression of IRAK-M may also be detrimental on local intrusion of PAMPs or bacteria, negatively regulates the LPS-induced and TLRs-mediated inflammation and results in immunosuppression in periprosthetic tissue, which may predispose to implant-associated infections.

IRAK-M in macrophages around septically and aseptically loosened hip implants.

The most common long-term complication of joint arthroplasty is loosening, which is mediated by chronic inflammatory cytokines produced by macrophages stimulated by implant-derived debris and eventually bacterial components adherent to such debris. In this study, antiinflammatory interleukin-1 receptor-associated kinase-M (IRAK-M) was studied in macrophages in interface membranes in vivo using immunohistochemical staining and in titanium particle-stimulated macrophages in vitro using reverse transcriptase-polymerase chain reaction. Results show that the interface membranes of septically and aseptically loosened prosthesis express more IRAK-M protein than control membranes from osteoarthritic patient and that IRAK-M mRNA-levels increase upon particle stimulation. These findings suggest that, the upregulation of IRAK-M in macrophages is involved in the local immunosuppression around implants, and may contribute to septic and aseptic implant loosening.